The checkbox has the following options:

theme string

default: null, inherited from parent

Sets the color scheme (swatch) for all instances of this widget. It accepts a single letter from a-z that maps to the swatches included in your theme. By default, it will inherit the same swatch color as it's parent container if not explicitly set. This option is also exposed as a data attribute: data-theme="a"

$("input[type='checkbox']").checkboxradio({ theme: "a" });